Fifth wheel coupling

ABSTRACT

A fifth wheel coupling ( 4 ) for coupling a tractor ( 2 ) and a semi-trailer ( 3 ) of a tractor-trailer unit ( 1 ) comprises a coupling device arranged on the tractor ( 2 ) for receiving and arresting a king journal fastened to the semi-trailer ( 3 ). In order to achieve the best possible swiveling properties at a design of low complexity, there is provided as a fifth wheel coupling a ball-shape coupling ( 4 ) with a coupling ball ( 5 ) and an associated holding-down device ( 6 ) on the one hand and a ball cup ( 7 ) enclosing the coupling ball ( 5 ) in the coupling position and the attached butt part ( 8 ) on the other hand, with the coupling ball ( 5 ) and the holding-down device ( 6 ) replacing the coupling device and the ball cup ( 7 ) and the butt part ( 8 ) replacing the king journal.

FIELD OF THE INVENTION

[0001] The invention relates to a fifth wheel coupling in order to couple a semi-trailer tractor and a semi-trailer of a tractor-trailer unit with a coupling device arranged on the semi-trailer tractor for the purpose of receiving and arresting a king journal.

DESCRIPTION OF THE PRIOR ART

[0002] Known fifth wheel couplings comprise a coupling plate with a coupling opening as the coupling device and a coupling claw which arrests the coupling opening, with the king journal of the semi-trailer which rests on the coupling plate with a sliding plate engaging in the coupling opening and being enclosed in the coupling position by the coupling claw. In addition to a swiveling movement of the semi-trailer relative to the semi-trailer tractor about a vertical axis, such fifth wheel couplings allow a swiveling about a transversal axis up to approx. 10°. However, they hardly allow any swiveling about a longitudinal axis, as a result of which the semi-trailer tractor lacks cross-country mobility. In order to improve the swiveling capacities it is therefore necessary to flexibly support the coupling device on the tractor chassis itself. This, however, is relatively complex and requires a high amount of maintenance and is unsatisfactory concerning the demand for similar swiveling movements to all sides, on which the cross-country mobility of the semi-trailer tractor depends.

SUMMARY OF THE INVENTION

[0003] The invention is therefore based on the object of providing a fifth wheel coupling of the kind mentioned above which offers the best possible swiveling properties at a comparatively simple arrangement.

[0004] The invention achieves this object substantially by using a ball-shaped coupling with a coupling ball and an associated holding down device on the one hand and a ball cup enclosing the coupling ball in the coupling position and comprising an attached butt part on the other hand, with the coupling ball and the holding down device replacing the coupling device or the king journal and ball cup and the butt part replacing the king journal or the coupling device. Ball-shaped couplings are superior with respect to other trailer couplings especially by their low amount of constructional complexity and their relatively wide swiveling ranges, which advantages can be also used in a rational fashion by using a ball-shaped coupling as a fifth wheel coupling for coupling a semi-trailer tractor and a semi-trailer, such that the coupling ball is used together with the associated holding-down device as a coupling device on the tractor side and the ball cup with its butt part forms the king journal. It is understood that the coupling ball and the ball cup can also be exchanged, so that in this case the coupling ball with the holding-down device is provided as a king journal on the trailer side and the ball cup with the butt part is provided as the coupling device on the tractor side. In the case of an opened holding-down device, the semi-trailer can be coupled without any difficulties onto or off the semi-trailer tractor and in the coupled position the holding-down device which is swiveled or pushed inwardly in the arrested position prevents any inadvertent lift-off of the coupling ball and ball cup. The cooperation of coupling ball and ball cup allow a swiveling movement of the trailer relative to the tractor virtually about any desired axis, so that in addition to the usual swivelability about a vertical axis for maneuvering the tractor-trailer unit it is also ensured that swiveling can be performed within very large angular ranges about a transversal axis and, especially, about a longitudinal axis. Tractor-trailer units which are equipped with such ball-shape couplings therefore offer full cross-country mobility.

[0005] A favorable construction is obtained when the butt part which is attached in the lateral area of the ball cup forms a cup-averted fastening end, with a free space being left for a cooperation of ball cup and holding-down device in the apex zone of the ball cup. This fastening end allows a versatile and sturdy connection of the ball cup via the butt part on the chassis or the like of the semi-trailer or the tractor. The free space in the apex zone of the ball cup prevents any undesirable limitation in the swiveling possibilities of the ball cup relative to the coupling ball. Due to the association of the holding-down device with the coupling ball, said swiveling movement is connected with a relative movement of the ball cup not only with respect to the coupling ball but also with respect to the holding-down device, so that the ball cup with its butt parts requires a respective play of movement relative to the holding-down device so as to avoid impairing the desired swiveling ranges, especially with respect to a swiveling movement about the longitudinal and transversal axes.

[0006] If the fastening end of the butt part comprises a connecting flange and/or connecting journal which is coaxial to the ball cup and if an intermediate space is provided as a free space between the fastening end and the ball cup, favorable load conditions are obtained during the absorption of the supporting and tractive forces and the ball cup forms with its head-shaped butt part a high-strength, compact and easy-to-mount component.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The subject matter of the invention is schematically shown in the drawings, wherein:

[0008]FIG. 1 shows a side view of a tractor-trailer unit equipped with the fifth wheel coupling in accordance with the invention;

[0009]FIG. 2 shows the relevant parts of the fifth wheel coupling in a partly sectional side view, and

[0010]FIG. 3 shows the ball cup with the attached butt part of the fifth wheel coupling in accordance with the invention in a graphical representation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] A tractor-trailer unit 1 consisting of a tractor 2 and a semi-trailer 3 comprises a ball coupling 4 with a coupling ball 5 and an associated holding-down device 6 on the one hand and a ball cup 7 and an attached butt part 8 on the other hand for coupling the tractor 2 and the semi-trailer 3. The coupling ball 5 and the holding-down device resting in a swivelably adjustable fashion on a pillow block 9 are arranged by way of a coupling support 10 on the vehicle chassis 11 of the tractor 2 and the ball cup 7 is fastened via its butt part 8 to a mounting plate 12 of the trailer chassis 13. In the illustrated coupling position the ball cup 7 encloses the coupling ball 5 from above and is arrested in this coupling position by the swiveled-in holding device 6, with the holding-down device 6 being held in a swivelable manner about a horizontal axis via a bearing bolt 14. It can be secured through a stop securing device 15. After the detachment of said stop securing device 15 and the rearward swiveling of the holding-down device 6, the ball coupling 4 is free and the semi-trailer 3 can be uncoupled from or coupled to the tractor 2 effortlessly.

[0012] As is shown especially in FIGS. 2 and 3, the butt part 8 is attached in the side region 16 of the ball cup 7 and forms a cup-averted fastening end 17 comprising a connecting flange 18 which is coaxial to the ball cup 7 and comprises a connecting journal 19, which fastening end 17 allows a simple, but stable connection of the ball cup 7 on the mounting plate 12 of the trailer 3. An intermediate space 21 is provided as a free space for the holding-down device 6 between the fastening end 17 and the ball cup 7 above its apex zone 20, so that the holding-down device 6 which acts in the arrested position outside on the ball cup 7 is provided with a free play of movement relative to the ball cup 7 and the butt part 8 and there is no impairment to the swiveling range of the ball cup 7 with respect to the coupling ball 5 during swiveling movements, especially about a longitudinal or transversal axis of the tractor 1. 

1. A fifth wheel coupling (4) in order to couple a semi-trailer tractor (2) and a semi-trailer (3) of a tractor-trailer unit (1) with a coupling device arranged on the semi-trailer tractor (2) for the purpose of receiving and arresting a king journal fastened to the semi-trailer (3), characterized by the use of a ball-shape coupling (4) with a coupling ball (5) and an associated holding-down device (6) on the one hand and a ball cup (7) enclosing the coupling ball (5) in the coupling position and the attached butt part (8) on the other hand, with the coupling ball (5) and the holding-down device (6) replacing the coupling device or the king journal and the ball cup (7) and the butt part (8) replacing the king journal or the coupling device.
 2. A fifth wheel coupling as claimed in claim 1, characterized in that the butt part (8) attached in the side region (16) of the ball cup (17) forms a cup-averted fastening end (17), with a free space for the cooperation of ball cup (7) and holding-down device (6) being provided in the apex zone (20) of the ball cup (7).
 3. A fifth wheel coupling as claimed in claim 2, characterized in that the fastening end (17) of the butt part (8) comprises a connecting flange (18) and/or connecting journal (19) which is coaxial to the ball cup (7) and an intermediate space (21) is provided as a free space between the fastening end (17) and the ball cup (7). 